Endovascular stent-graft with fatigue-resistant lateral tube

ABSTRACT

A stent-graft ( 20 ) comprises strut members ( 30 ) and a graft member ( 32 ), which is fixed to the strut members ( 30 ). The strut members ( 30 ) and the graft member ( 32 ) are arranged so as to define, when the stent-graft ( 20 ) is in a radially-expanded state: a main tube ( 40 ), which is shaped so as to define a main lumen ( 42 ); and a lateral tube ( 50 ), which (a) has (i) a distal end ( 52 ) and (ii) a proximal end ( 54 ) that is joined to a lateral wall ( 56 ) of the main tube ( 40 ) at a junction ( 60 ), (b) is shaped so as to define a lateral lumen ( 62 ) that is in fluid communication with the main lumen ( 42 ), and (c) defines a central longitudinal axis ( 64 ). The strut members ( 30 ) that define the lateral tube ( 50 ) are shaped so as to define two to four non-contiguous arcuate members ( 70 ), which (a) are centered around the central longitudinal axis ( 64 ); and (b) collectively subtend at least 150 degrees around the central longitudinal axis ( 64 ).

CROSS-REFERENCE TO RELATED APPLICATIONS

The present application claims priority from U.S. ProvisionalApplication 62/093,497, filed Dec. 18, 2014, which is assigned to theassignee of the present application and is incorporated herein byreference.

FIELD OF THE APPLICATION

The present invention relates generally to implantable medical devices,and specifically to delivery tools and implantable stent-grafts.

BACKGROUND OF THE APPLICATION

Endovascular prostheses are sometimes used to treat aortic aneurysms.Such treatment includes implanting a stent or stent-graft within thediseased vessel to bypass the anomaly. An aneurysm is a sac formed bythe dilation of the wall of the artery. Aneurysms may be congenital, butare usually caused by disease or, occasionally, by trauma. Aorticaneurysms which commonly form between the renal arteries and the iliacarteries are referred to as abdominal aortic aneurysms (“AAAs”). Otheraneurysms occur in the aorta, such as thoracic aortic aneurysms (“TAAs”)and aortic uni-iliac (“AUI”) aneurysms. A TAA may occur downstream theaortic arch, i.e., in the descending aorta. Alternatively, a TAA mayoccur in the aortic arch itself, where the aorta branches to supply thebrachiocephalic, left carotid and subclavian arteries, or may occur inthe ascending aorta.

Endo-Vascular Aneurysm Repair (EVAR) has transformed the practice oftreatment of aortic aneurysms from an open surgical approach to a muchless invasive surgical approach. The first step of an endovascularintervention usually requires introducing a delivery system into thevasculature of a subject. If the crossing profile, i.e., the externaldiameter, of the delivery system is 24 Fr or lower (3 Fr=1 millimeter),a true percutaneous approach may be used, because vascular closuredevices are available for proper closure of such puncture sites.

Blood vessels occasionally weaken or even rupture. For example, in theaortic artery, the vascular wall can weaken or tear, resulting indangerous conditions such as aneurysm and dissection. Treatment of suchconditions can be performed by implanting a prosthesis within thevascular system using minimally-invasive surgical procedures. Anendoluminal prosthesis typically includes one or more stents affixed tograft material and is delivered to the treatment site by endovascularinsertion. Once the endoluminal prosthesis is radially enlarged, itshould remain in place indefinitely by self-attachment to the vesselwall, acting as a substitute vessel for the flow of blood. or otherfluids.

Aortic dissection is a tear or partial tear in the inner wall of theaorta, which causes blood to flow between the layers of the wall of theaorta, forcing the layers apart. Aortic dissections may he divided intotwo types in accordance with the Stanford classification: Type Adissections involve the ascending aorta and/or aortic arch, and possiblythe descending aorta. Type B dissections involve the descending aorta orthe arch (distal to right brachiocephalic artery origin), withoutinvolvement of the ascending aorta.

SUMMARY OF THE APPLICATION

In some embodiments of the present invention, a stent-graft comprises aplurality of structural strut members and a graft member, which arearranged so as to define a main tube and a lateral tube, when thestent-graft is in a radially-expanded state. The lateral tube has aproximal end that is joined to a lateral wall of the main tube. When thestent-graft is in the radially-expanded state, the structural strutmembers that the define lateral tube are shaped so as to define two tosix, typically two to four, non-contiguous arcuate members, which (a)are centered around a central longitudinal axis of the lateral tube, and(b) collectively subtend at least 150 degrees around the centrallongitudinal axis. Typically, the arcuate members are arranged so as toprovide respective circumferential gaps betweencircumferentially-adjacent ones of the arcuate members, when thestent-graft is in the radially-expanded state. This configuration of thestructural stent members of the lateral tube tends to increase thefatigue resistance of the lateral tube during long-term implantation ofthe stent-graft in an aneurysmal artery.

For some applications, the structural strut members that define thelateral tube are shaped so as to define respective linking members forthe arcuate members. The linking members link the arcuate members to thea junction at which the proximal end of the lateral tube is joined tothe main tube, such as with one or more structural strut members thatsurround the proximal end of the lateral tube. For some of theseapplications, the linking members form respective angles with therespective arcuate members, which angles have an average of 30 to 90degrees, when the stent-graft is in the radially-expanded state. In someconfigurations, the average angle is 85 to 90 degrees, e.g., 90 degrees,while for other applications, the average angle is 30 to 60 degrees,e.g., about 45 degrees.

For some applications, the arcuate members are disposed at a same axialposition along the lateral tube, when the stent-graft is in theradially-expanded state. Typically, the arcuate members are disposedwith 3 mm of a distal end of the structural strut members that definethe lateral tube, when the stent-graft is in the radially-expandedstate. For example, the arcuate members may be disposed at the distalend of the structural strut members that define the lateral tube, whenthe stent-graft is in the radially-expanded state. Typically, thearcuate members are disposed with 3 mm of a distal end of a portion ofthe graft member that defines the lateral tube, when the stent-graft isin the radially-expanded state. For example, the arcuate members may bedisposed at the distal end of the portion of the graft member thatdefines the lateral tube, when the stent-graft is in theradially-expanded state.

There is therefore provided, in accordance with an inventive concept 1of the present invention, apparatus comprising an endovascularstent-graft, which is configured to transition from aradially-compressed delivery state to a radially-expanded state, andwhich comprises:

-   -   a plurality of structural strut members; and    -   a graft member, which comprises one or more substantially        blood-impervious flexible sheets, and which is fixed to the        structural strut members,    -   wherein the structural strut members and the graft member are        arranged so as to define, when the stent-graft is in the        radially-expanded state:        -   a main tube, which is shaped so as to define a main lumen,            and        -   a lateral tube, which (a) has (i) a distal end and (ii) a            proximal end that is joined to a lateral wall of the main            tube at a junction, (b) is shaped so as to define a lateral            lumen that is in fluid communication with the main lumen,            and (c) defines a central longitudinal axis, and    -   wherein, when the stent-graft is in the radially-expanded state,        the structural strut members that define the lateral tube are        shaped so as to define two to four non-contiguous arcuate        members, which (a) are centered around the central longitudinal        axis, and (b) collectively subtend at least 150 degrees around        the central longitudinal axis.

Inventive concept 2. The apparatus according to inventive concept 1.wherein the arcuate members collectively subtend at least 180 degreesaround the central longitudinal axis, when the stent-graft is in theradially-expanded state.

Inventive concept 3. The apparatus according to inventive concept 2,wherein the arcuate members collectively subtend at least 210 degreesaround the central longitudinal axis, when the stent-graft is in theradially-expanded state.

Inventive concept 4. The apparatus according to inventive concept 1,wherein at least one of the arcuate members alone subtends at least 60degrees around the central longitudinal axis, when the stent-graft is inthe radially-expanded state.

Inventive concept 5. The apparatus according to inventive concept 1,wherein the arcuate members are disposed at a same axial position alongthe lateral tube, when the stent-graft is in the radially-expandedstate.

Inventive concept 6. The apparatus according to inventive concept 1,wherein at least two of the arcuate members are disposed at respectivedifferent axial positions along the lateral tube, when the stent-graftis in the radially-expanded state.

Inventive concept 7. The apparatus according to inventive concept 1,wherein the arcuate members are disposed with 3 mm of a distal end ofthe structural strut members that define the lateral tube, when thestent-graft is in the radially-expanded state.

Inventive concept 8. The apparatus according to inventive concept 7,wherein the arcuate members are disposed at the distal end of thestructural strut members that define the lateral tube, when thestent-graft is in the radially-expanded state.

Inventive concept 9. The apparatus according to inventive concept 1,wherein the arcuate members are disposed with 3 mm of a distal end of aportion of the graft member that defines the lateral tube, when thestent-graft is in the radially-expanded state.

Inventive concept 10. The apparatus according to inventive concept 9,wherein the arcuate members are disposed at the distal end of theportion of the graft member that defines the lateral tube, when thestent-graft is in the radially-expanded state.

Inventive concept 11. The apparatus according to inventive concept 1,wherein when the main tube is in a radially-expanded state thereof andthe lateral tube is in a compressed delivery state thereof, the arcuatemembers define a portion of a generally tubular outer surface of themain tube.

Inventive concept 12. The apparatus according to inventive concept 1,wherein the apparatus further comprises a branching stent-graft, whichis configured to form a blood-tight seal with the lateral tube, when thestent-graft is in the radially-expanded state and the branchingstent-graft is in a radially-expanded state.

Inventive concept 13. The apparatus according to inventive concept 1,wherein a ratio of (a) an average circumference of the main tube and (b)an average circumference of the lateral tube is between 1:1 and 5:1,when the stent-graft is in the radially-expanded state.

Inventive concept 14. The apparatus according to inventive concept 1,wherein a length of the lateral tube is between 10% and 30% of anaverage circumference of the lateral tube, when the stent-graft is inthe radially-expanded state.

Inventive concept 15. The apparatus according to inventive concept 1,wherein a circumference of the lateral tube at the proximal end of thelateral tube is between 5% and 30% greater than a circumference of thelateral tube at the distal end of the lateral tube, when the stent-graftis in the radially-expanded state.

Inventive concept 16. The apparatus according to inventive concept 1,wherein an angle between the central longitudinal axis of the lateraltube and a central longitudinal axis of the main tube is greater than 80degrees, when the stent-graft is in the radially-expanded state.

Inventive concept 17. The apparatus according to inventive concept 1,wherein an angle between the central longitudinal axis of the lateraltube and a central longitudinal axis of the main tube is between 60 and80 degrees, when the stent-graft is in the radially-expanded state.

Inventive concept 18. The apparatus according to inventive concept 1,wherein an angle between the central longitudinal axis of the lateraltube and a central longitudinal axis of the main tube is between 30 and60 degrees, when the stent-graft is in the radially-expanded state.

Inventive concept 19. The apparatus according to inventive concept 1,wherein the main tube has proximal and distal ends, and wherein acircumference of the proximal end of the main tube is 3 to 10 cm, whenthe stent-graft is in the radially-expanded state.

Inventive concept 20. The apparatus according to inventive concept 19,wherein a circumference of the distal end of the main tube is 6 to 12cm, when the stent-graft is in the radially-expanded state.

Inventive concept 21. The apparatus according to inventive concept 1,wherein a length of the main tube is 4 to 15 cm.

Inventive concept 22. The apparatus according to inventive concept 1,wherein the one or more of the structural strut members comprise aflexible metal.

Inventive concept 23. The apparatus according to inventive concept 22,wherein the metal comprises a superelastic alloy.

Inventive concept 24. The apparatus according to inventive concept 23,wherein the alloy comprises Nitinol.

Inventive concept 25. The apparatus according to inventive concept 1,wherein the one or more flexible sheets comprise polyethyleneterephthalate.

Inventive concept 26. The apparatus according to inventive concept 1,wherein the one or more flexible sheets comprise expandedpolytetrafluoroethylene (PTFE).

Inventive concept 27. The apparatus according to any one of inventiveconcepts 1-26, wherein the arcuate members are arranged so as to providerespective circumferential gaps between circumferentially-adjacent onesof the arcuate members, when the stent-graft is in the radially-expandedstate.

Inventive concept 28. The apparatus according to inventive concept 27,wherein the arcuate members collectively subtend no more than 350degrees around the central longitudinal axis, when the stent-graft is inthe radially-expanded state.

Inventive concept 29. The apparatus according to inventive concept 28.wherein the arcuate members collectively subtend no more than 340degrees around the central longitudinal axis, when the stent-graft is inthe radially-expanded state.

Inventive concept 30. The apparatus according to inventive concept 27,wherein each of the circumferential gaps measures at least 10 degrees,when the stent-graft is in the radially-expanded state.

Inventive concept 31. The apparatus according to inventive concept 30,wherein each of the circumferential gaps measures at least 20 degrees,when the stent-graft is in the radially-expanded state.

Inventive concept 32. The apparatus according to inventive concept 27,wherein the arcuate members are disposed at a same axial position alongthe lateral tube, when the stent-graft is in the radially-expandedstate.

Inventive concept 33. The apparatus according to inventive concept 32,wherein respective areas of the lateral tube, which (a)circumferentially correspond with the gaps and (b) extend from the axialposition of the arcuate members along at least 50% of a distance betweenthe axial position of the arcuate members and the junction, are freefrom the structural strut members, when the stent-graft is in theradially-expanded state.

Inventive concept 34. The apparatus according to inventive concept 33,wherein the respective areas extend from the arcuate members along 60%of the distance.

Inventive concept 35. The apparatus according to inventive concept 34,wherein the respective areas extend from the arcuate members along 100%of the distance.

Inventive concept 36. The apparatus according to any one of inventiveconcepts 1-26, wherein the structural strut members that define thelateral tube are shaped so as to define respective linking members forthe arcuate members, which linking members link the arcuate members tothe junction.

Inventive concept 37. The apparatus according to inventive concept 36,wherein, when the stent-graft is in the radially-expanded state, thelateral tube is free from the structural strut members, except for thearcuate members and the linking members, in an area that (a) extendsentirely around the central longitudinal axis and (b) extends from thedistal end of the lateral tube along at least 50% of a distance betweenthe distal end of the lateral tube and the junction.

Inventive concept 38. The apparatus according to inventive concept 37,wherein, when the stent-graft is in the radially-expanded state, thelateral tube is free from the structural strut members, except for thearcuate members, the linking members, and any of the structural strutmembers that surround the proximal end of the lateral tube at thejunction.

Inventive concept 39. The apparatus according to inventive concept 36,wherein an average length of the linking members equals at least 80% ofa length of the lateral tube, when the stent-graft is in theradially-expanded state.

Inventive concept 40. The apparatus according to inventive concept 36,wherein, when the stent-graft is in the radially-expanded state,respective points on the linking members and respective juncture pointsbetween the link members and the arcuate members define respectivelines, which lines form respective angles with the respective arcuatemembers, which angles have an average of 30 to 90 degrees, and whichpoints on the linking members are at 30% of a distance between the axialposition of the arcuate members and the junction.

Inventive concept 41. The apparatus according to inventive concept 40,wherein an average length of the linking members equals at least 80% ofa length of the lateral tube, when the stent-graft is in theradially-expanded state.

Inventive concept 42. The apparatus according to inventive concept 40,wherein the average is 85 to 90 degrees.

Inventive concept 43. The apparatus according to inventive concept 42,wherein the average is 90 degrees.

Inventive concept 44. The apparatus according to inventive concept 40,wherein the average is 30 to 60 degrees.

Inventive concept 45. The apparatus according to inventive concept 40,wherein the linking members form respective angles with the respectivearcuate members, which angles have an average of 30 to 90 degrees, whenthe stent-graft is in the radially-expanded state.

Inventive concept 46. The apparatus according to inventive concept 45,wherein the average is 85 to 90 degrees.

Inventive concept 47. The apparatus according to inventive concept 46,wherein the average is 90 degrees.

Inventive concept 48. The apparatus according to inventive concept 45,wherein the average is 30 to 60 degrees.

Inventive concept 49. The apparatus according to inventive concept 36,wherein each of the linking members is connected to its respectivearcuate member at a juncture point at a location along the arcuatemember that is within a number of degrees of a circumferential center ofthe arcuate member around the central circumferential axis, which numberof degrees is equal to 40% of a total number of degrees of the arcuatemember.

Inventive concept 50. The apparatus according to inventive concept 49,wherein the location along the arcuate member is at the circumferentialcenter of the arcuate member.

Inventive concept 51. The apparatus according to inventive concept 36,wherein, when the stent-graft is in the radially-expanded state, one ormore of the structural strut members (a) completely surround theproximal end of the lateral tube at the junction and (b) are connectedto the linking members.

Inventive concept 52. The apparatus according to any one of inventiveconcepts 1-26, wherein one or more of the structural strut memberscompletely surround the proximal end of the lateral tube at thejunction, when the stent-graft is in the radially-expanded state.

Inventive concept 53. The apparatus according to inventive concept 52,

-   -   wherein the structural strut members that define the main tube        are shaped so as a plurality of circumferential stent springs,        each of which is shaped so as to define a plurality of stent        cells, and    -   wherein one of the stent cells of one of the circumferential        stent springs is defined by the one or more of the structural        strut members that completely surround the proximal end of the        lateral tube at the junction, when the stent-graft is in the        radially-expanded. state.

Inventive concept 54. The apparatus according to inventive concept 53,wherein the stent cells of the one of the circumferential stent springsare diamond-shaped, when the stent-graft is in the radially-expandedstate.

Inventive concept 55. The apparatus according to inventive concept 54,wherein the diamond-shaped stent cells have respective, differentdimensions, when the stent-graft is in the radially-expanded state.

Inventive concept 56. The apparatus according to inventive concept 55,wherein a largest one of the diamond-shaped stent cells is at least 100%greater in surface area than a smallest one of the diamond-shaped stentcells, which largest one of the diamond-shaped stent cells is the one ofthe stent cells that is defined by the one or more of the structuralstrut members that completely surround the proximal end of the lateraltube at the junction, when the stent-graft is in the radially-expandedstate.

Inventive concept 57. The apparatus according to inventive concept 56,

Inventive concept wherein the lateral tube is a first lateral tube, thedistal and proximal ends are first distal and proximal ends, thejunction is a first junction, the lateral lumen is a first laterallumen, the central longitudinal axis is a first central longitudinalaxis, and the arcuate members are first arcuate members,

-   -   wherein the structural strut members and the graft member are        arranged so as to define, when the stent-graft is in the        radially-expanded state, a second lateral tube, which (a)        has (i) a second distal end and (ii) a second proximal end that        is joined to the lateral wall of the main tube at a second        junction, (b) is shaped so as to define a second lateral lumen        that is in fluid communication with the main lumen, and (c)        defines a second central longitudinal axis,    -   wherein, when the stent-graft is in the radially-expanded state,        the structural strut members that define the second lateral tube        are shaped so as to define two to four non-contiguous second        arcuate members, which (a) are centered around the second        central longitudinal axis, and (b) collectively subtend at least        150 degrees around the second central longitudinal axis, and    -   wherein the smallest one of the diamond-shaped stent cells        completely surrounds the second proximal end of the second        lateral tube at the second junction, when the stem-graft is in        the radially-expanded state.

There is further provided, in accordance with an inventive concept 58 ofthe present invention, a method for treating a subject, comprising:

-   -   transvascularly introducing an endovascular stent-graft into a        blood vessel of the subject while the stent-graft is in a        radially-compressed delivery state, which stent-graft        comprises (a) a plurality of structural strut members, and (b) a        graft member, which comprises one or more substantially        blood-impervious flexible sheets, and which is fixed to the        structural strut members: and    -   transitioning the stent-graft to a radially-expanded state, in        which:        -   the structural strut members and the graft member are            arranged so as to define (x) a main tube, which is shaped so            as to define a main lumen, and (y) a lateral tube, which (a)            has (i) a distal end and (ii) a proximal end that is joined            to a lateral wall of the main tube at a junction, (b) is            shaped so as to define a lateral lumen that is in fluid            communication with the main lumen, and (c) defines a central            longitudinal axis, and        -   the structural strut members that define the lateral tube            are shaped so as to define two to four non-contiguous            arcuate members, which (a) are centered around the central            longitudinal axis, and (b) collectively subtend at least 150            degrees around the central longitudinal axis.

Inventive concept 59. The method according to inventive concept 58,wherein transitioning comprises transitioning the stent-graft to theradially-expanded state in which the arcuate members collectivelysubtend at least 180 degrees around the central longitudinal axis.

Inventive concept 60. The method according to inventive concept 59,wherein transitioning comprises transitioning the stent-graft to theradially-expanded state in which the arcuate members collectivelysubtend at least 210 degrees around the central longitudinal axis.

Inventive concept 61. The method according to inventive concept 58,wherein transitioning comprises transitioning the stent-graft to theradially-expanded state in which at least one of the arcuate membersalone subtends at least 60 degrees around the central longitudinal axis.

Inventive concept 62. The method according to inventive concept 58,wherein transitioning comprises transitioning the stent-graft to theradially-expanded state in which the arcuate members are disposed at asame axial position along the lateral tube.

Inventive concept 63. The method according to inventive concept 58,wherein transitioning comprises transitioning the stent-graft to theradially-expanded state in which at least two of the arcuate members aredisposed at respective different axial positions along the lateral tube.

Inventive concept 64. The method according to inventive concept 58,wherein transitioning comprises transitioning the stent-graft to theradially-expanded state in which the arcuate members are disposed with 3mm of a distal end of the structural strut members that define thelateral tube.

Inventive concept 65. The method according to inventive concept 64,wherein transitioning comprises transitioning the stent-graft to theradially-expanded state in which the arcuate members are disposed at thedistal end of the structural strut members that define the lateral tube.

Inventive concept 66. The method according to inventive concept 58,wherein transitioning comprises transitioning the stent-graft to theradially-expanded state in which the arcuate members are disposed with 3mm of a distal end of a portion of the graft member that defines thelateral tube.

Inventive concept 67. The method according to inventive concept 66,wherein transitioning comprises transitioning the stent-graft to theradially-expanded state in which the arcuate members are disposed at thedistal end of the portion of the graft member that defines the lateraltube.

Inventive concept 68. The method according to inventive concept 58,wherein transitioning comprises:

-   -   transitioning the main tube to a radially-expanded state thereof        while the lateral tube remains in a compressed delivery state        thereof; in which the arcuate members define a portion of a        generally tubular outer surface of the main tube; and    -   thereafter, transitioning the lateral tube to a        radially-expanded state thereof, such that the stent-graft is in        the radially-expanded state thereof.

Inventive concept 69. The method according to inventive concept 58,wherein transitioning comprises transitioning the stent-graft to theradially-expanded state in which a ratio of (a) an average circumferenceof the main tube and (b) an average circumference of the lateral tube isbetween 1:1 and 5:1.

Inventive concept 70. The method according to inventive concept 58,wherein transitioning comprises transitioning the stent-graft to theradially-expanded state in which a length of the lateral tube is between10% and 30% of an average circumference of the lateral tube.

Inventive concept 71. The method according to inventive concept 58,wherein transitioning comprises transitioning the stent-graft to theradially-expanded state in which a circumference of the lateral tube atthe proximal end of the lateral tube is between 5% and 30% greater thana circumference of the lateral tube at the distal end of the lateraltube.

Inventive concept 72. The method according to inventive concept 58,wherein transitioning comprises transitioning the stent-graft to theradially-expanded state in which an angle between the centrallongitudinal axis of the lateral tube and a central longitudinal axis ofthe main tube is greater than 80 degrees.

Inventive concept 73. The method according to inventive concept 58,wherein transitioning comprises transitioning the stent-graft to theradially-expanded state in which an angle between the centrallongitudinal axis of the lateral tube and a central longitudinal axis ofthe main tube is between 60 and 80 degrees.

Inventive concept 74. The method according to inventive concept 58,wherein transitioning comprises transitioning the stent-graft to theradially-expanded state in which an angle between the centrallongitudinal axis of the lateral tube and a central longitudinal axis ofthe main tube is between 30 and 60 degrees.

Inventive concept 75. The method according to inventive concept 58,wherein the main tube has proximal and distal ends, and whereintransitioning comprises transitioning the stent-graft to theradially-expanded state in which a circumference of the proximal end ofthe main tube is 3 to 10 cm.

Inventive concept 76. The method according to inventive concept 75,wherein transitioning comprises transitioning the stent-graft to theradially-expanded state in which a circumference of the distal end ofthe main tube is 6 to 12 cm.

Inventive concept 77. The method according to inventive concept 58,

-   -   wherein transvascularly introducing the stent-graft comprises        transvascularly introducing the stent-graft while the        stent-graft is restrained in the radially-compressed delivery        state within an elongate delivery tube, and    -   wherein transitioning the stent-graft to a radially-expanded        state comprises releasing the stent-graft from the elongate        delivery tube.

Inventive concept 78. The method according to inventive concept 77,wherein a ratio of

-   (a) an average circumference of the main tube when in a    radially-expanded state thereof to-   (b) an inner circumference of the delivery tube is at least 5.

Inventive concept 79. The method according to inventive concept 58,wherein transitioning comprises transitioning the stent-graft to theradially-expanded state in which the arcuate members are arranged so asto provide respective circumferential gaps betweencircumferentially-adjacent ones of the arcuate members.

Inventive concept 80. The method according to inventive concept 79,wherein transitioning comprises transitioning the stent-graft to theradially-expanded state in which the arcuate members collectivelysubtend no more than 350 degrees around the central longitudinal axis.

Inventive concept 81. The method according to inventive concept 80,wherein transitioning comprises transitioning the stent-graft to theradially-expanded state in which the arcuate members collectivelysubtend no more than 340 degrees around the central longitudinal axis.

Inventive concept 82. The method according to inventive concept 79,wherein transitioning comprises transitioning the stent-graft to theradially-expanded state in which each of the circumferential gapsmeasures at least 10 degrees.

Inventive concept 83. The method according to inventive concept 82,wherein transitioning comprises transitioning the stent-graft to theradially-expanded state in which each of the circumferential gapsmeasures at least 20 degrees.

Inventive concept 84. The method according to inventive concept 79,wherein transitioning comprises transitioning the stent-graft to theradially-expanded state in which the arcuate members are disposed at asame axial position along the lateral tube.

Inventive concept 85. The method according to inventive concept 84,wherein transitioning comprises transitioning the stent-graft to theradially-expanded state in which respective areas of the lateral tube,which (a) circumferentially correspond with the gaps and (b) extend fromthe axial position of the arcuate members along at least 50% of adistance between the axial position of the arcuate members and thejunction, are free from the structural strut members.

Inventive concept 86. The method according to inventive concept 85,wherein transitioning comprises transitioning the stent-graft to theradially-expanded state in which the respective areas extend from thearcuate members along 60% of the distance.

Inventive concept 87. The method according to inventive concept 86,wherein transitioning comprises transitioning the stem-graft to theradially-expanded state in which the respective areas extend from thearcuate members along 100% of the distance.

Inventive concept 88. The method according to inventive concept 58,wherein the structural strut members that define the lateral tube areshaped so as to define respective linking members for the arcuatemembers, which linking members link the arcuate members to the junction.

Inventive concept 89. The method according to inventive concept 88,wherein transitioning comprises transitioning the stent-graft to theradially-expanded state in which the lateral tube is free from thestructural strut members, except for the arcuate members and the linkingmembers, in an area that (a) extends entirely around the centrallongitudinal axis and (b) extends from the distal end of the lateraltube along at least 50% of a distance between the distal end of thelateral tube and the junction.

Inventive concept 90. The method according to inventive concept 89,wherein transitioning comprises transitioning the stent-graft to theradially-expanded state in which the lateral tube is free from thestructural strut members, except for the arcuate members, the linkingmembers, and any of the structural strut members that surround theproximal end of the lateral tube at the junction.

Inventive concept 91. The method according to inventive concept 88,wherein transitioning comprises transitioning the stent-graft to theradially-expanded state in which an average length of the linkingmembers equals at least 80% of a length of the lateral tube.

Inventive concept 92. The method according to inventive concept 88,wherein transitioning comprises transitioning the stent-graft to theradially-expanded state in which respective points on the linkingmembers and respective juncture points between the link members and thearcuate members define respective lines, which lines form respectiveangles with the respective arcuate members, which angles have an averageof 30 to 90 degrees, and which points on the linking members are at 30%of a distance between the axial position of the arcuate members and thejunction.

Inventive concept 93. The method according to inventive concept 92,wherein transitioning comprises transitioning the stent-graft to theradially-expanded state in which an average length of the linkingmembers equals at least 80% of a length of the lateral tube.

Inventive concept 94. The method according to inventive concept 92, reinthe average is 85 to 90 degrees.

Inventive concept 95. The method according to inventive concept 94,wherein the average is 90 degrees.

Inventive concept 96. The method according to inventive concept 92,wherein the average is 30 to 60 degrees.

Inventive concept 97. The method according to inventive concept 92,wherein transitioning comprises transitioning the stent-graft to theradially-expanded state in which the linking members form respectiveangles with the respective arcuate members, which angles have an averageof 30 to 90 degrees.

Inventive concept 98. The method according to inventive concept 97,wherein the average is 85 to 90 degrees.

Inventive concept 99. The method according to inventive concept 98,wherein the average is 90 degrees.

Inventive concept 100. The method according to inventive concept 97,wherein the average is 30 to 60 degrees.

Inventive concept 101. The method according to inventive concept 88,wherein transitioning comprises transitioning the stent-graft to theradially-expanded state in which each of the linking members isconnected to its respective arcuate member at a juncture point at alocation along the arcuate member that is within a number of degrees ofa circumferential center of the arcuate member around the centralcircumferential axis, which number of degrees is equal to 40% of a totalnumber of degrees of the arcuate member.

Inventive concept 102. The method according to inventive concept 101,wherein the location along the arcuate member is at the circumferentialcenter of the arcuate member.

Inventive concept 103. The method according to inventive concept 88,wherein transitioning comprises transitioning the stent-graft to theradially-expanded state in which one or more of the structural strutmembers (a) completely surround the proximal end of the lateral tube atthe junction and (b) are connected to the linking members.

Inventive concept 104. The method according to inventive concept 58,wherein transitioning comprises transitioning the stent-graft to theradially-expanded state in which one or more of the structural strutmembers completely surround the proximal end of the lateral tube at thejunction.

Inventive concept 105. The method according to inventive concept 104,

-   -   wherein the structural strut members that define the main tube        are shaped so as a plurality of circumferential stent springs,        each of which is shaped so as to define a plurality of stent        cells, and    -   wherein transitioning comprises transitioning the stent-graft to        the radially-expanded state in which one of the stent cells of        one of the circumferential stent springs is defined by the one        or more of the structural strut members that completely surround        the proximal end of the lateral tube at the junction.

Inventive concept 106. The method according to inventive concept 105,wherein transitioning comprises transitioning the stent-graft to theradially-expanded state in which the stent cells of the one of thecircumferential stent springs are diamond-shaped.

Inventive concept 107. The method according to inventive concept 106,wherein transitioning comprises transitioning the stent-graft to theradially-expanded state in which the diamond-shaped stent cells haverespective, different dimensions.

Inventive concept 108. The method according to inventive concept 107,wherein transitioning comprises transitioning the stent-graft to theradially-expanded state in which a largest one of the diamond-shapedstent cells is at least 100% greater in surface area than a smallest oneof the diamond-shaped stent cells, which largest one of thediamond-shaped stent cells is the one of the stent cells that is definedby the one or more of the structural strut members that completelysurround the proximal end of the lateral tube at the junction.

109. The method according to inventive concept 108,

-   -   wherein the lateral tube is a first lateral tube, the distal and        proximal ends are first distal and proximal ends, the junction        is a first junction, the lateral lumen is a first lateral lumen,        the central longitudinal axis is a first central longitudinal        axis, and the arcuate members are first arcuate members,    -   wherein transitioning comprises transitioning the stent-graft to        the radially-expanded state, in which:        -   the structural strut members and the graft member are            arranged so as to define a second lateral tube, which (a)            has (i) a second distal end and (ii) a second proximal end            that is joined to the lateral wall of the main tube at a            second junction, (b) is shaped so as to define a second            lateral lumen that is in fluid communication with the main            lumen, and (c) defines a second central longitudinal axis,            and        -   the structural strut members that define the second lateral            tube are shaped so as to define two to four non-contiguous            second arcuate members, which (a) are centered around the            second central longitudinal axis, and (b) collectively            subtend    -   at least 150 degrees around the second central longitudinal        axis, and    -   wherein the smallest one of the diamond-shaped stent cells        completely surrounds the second proximal end of the second        lateral tube at the second junction, when the stent-graft is in        the radially-expanded state.

Inventive concept 110. The method according to inventive concept 58,wherein transvascularly introducing the stent-graft into the bloodvessel comprises transvascularly introducing the stent-graft into anaorta of the subject.

Inventive concept 111. The method according to inventive concept 110,wherein transvascularly introducing the stent-graft into the aortacomprises transvascularly introducing the stent-graft into an aneurysmalaorta.

Inventive concept 112. The method according to inventive concept 58,further comprising:

-   -   transvascularly introducing a branching stent-graft through a        portion of the main tube and into a branching blood vessel while        the branching stent-graft is in a radially-compressed delivery        state thereof; and    -   transitioning the branching stent-graft to a radially-expanded        state thereof, in which the branching stent-graft forms a        blood-tight seal with the lateral tube.

Inventive concept 113. The method according to inventive concept 112,

-   -   wherein transvascularly introducing the stent-graft into the        blood vessel comprises transvascularly introducing the        stent-graft into an aneurysmal aorta of the subject, and    -   wherein transvascularly introducing the branching stent-graft        into the branching blood vessel comprises transvascularly        introducing the branching stent-graft into a visceral artery of        the subject.

Inventive concept 114. The method according to inventive concept 13,wherein the visceral artery is a renal artery.

Inventive concept 115. The method according to inventive concept 113,wherein the visceral artery is a superior mesenteric artery (SMA).

Inventive concept 116. The method according to inventive concept 113,wherein the visceral artery is a celiac artery.

The present invention will be more fully understood from the followingdetailed description of embodiments thereof, taken together with thedrawings, in which:

BRIEF DESCRIPTION OF THE DRAWINGS

FIGS. 1A-B are schematic illustrations of a portion of an endovascularstent-graft, in accordance with an application of the present invention;

FIG. 2A is a schematic illustration of another configuration of thestent-graft of FIGS. 1A-B, in accordance with an application of thepresent invention;

FIG. 2B, which is a schematic illustration of yet another configurationof stent-graft 20, in accordance with an application of the presentinvention;

FIGS. 3A-B are schematic illustrations of a portion of anotherendovascular stent-graft, in accordance with an application of thepresent invention;

FIGS. 4A-B are schematic illustrations of a portion of yet anotherendovascular stent-graft, in accordance with an application of thepresent invention;

FIGS. 5A and 5B, which are schematic illustrations of portions of thestent-grafts of FIGS. 1A-B and 4A-B, respectively, in accordance withrespective applications of the present invention; and

FIG. 6A-B are schematic illustrations of exemplary deployments of thestent-graft of FIGS. 3A-B, in accordance with respective applications ofthe present invention.

DETAILED DESCRIPTION OF APPLICATIONS

FIGS. 1A and 1B are schematic illustrations of a portion of anendovascular stent-graft 20, in accordance with an application of thepresent invention. Stent-graft 20 is configured to transition from aradially-compressed delivery state (not shown) to a radially-expandedstate (as shown in FIG. 1A). Stent-graft 20 comprises a plurality ofstructural strut members 30 and a graft member 32, which is fixed tostructural strut members 30.

Structural strut members 30 and graft member 32 are arranged so as todefine, when stent-graft 20 is in the radially-expanded state:

-   -   a main tube 40, which is shaped so as to define a main lumen 42,        and    -   a lateral tube 50, which (a) has (i) a distal end 52 and (ii) a        proximal end 54 that is joined to a lateral wall 56 of main tube        40 at a junction 60 (junction 60 is flush with the external        surface of main tube 40), (b) is shaped so as to define a        lateral lumen 62 that is in fluid communication with main lumen        42, and (c) defines a central longitudinal axis 64.

When stent-graft 20 is in the radially-expanded state, as shown in FIG.1A, structural strut members 30 that define lateral tube 50 are shapedso as to define two to six, typically two to four, non-contiguousarcuate members 70, which (a) are centered around central longitudinalaxis 64, and (b) collectively subtend at least 150 degrees aroundcentral longitudinal axis 64, such as at least 180 degrees, e.g., atleast 210 degrees around central longitudinal axis 64, such as at least300 degrees, e.g., at least 340 degrees. (It is to be understood thatnot all of structural strut members 30 that define lateral tube 50necessarily are shaped so as to define arcuate members 70; typically,only a portion of structural strut members 30 that define lateral tube50 are shaped so as to define arcuate members 70.) For example, in theconfiguration shown in FIGS. 1A and 1B, structural strut members 30 thatdefine lateral tube 50 are shaped so as to define exactly twonon-contiguous arcuate members 70, each of which subtends an angle α(alpha) around central longitudinal axis 64, such that they collectivelysubtend an angle equal to 2α (twice alpha). For some applications, atleast one of arcuate members 70 alone subtends at least 60 degreesaround central longitudinal axis 64 when stent-graft 20 is in theradially-expanded state. For example, in the configuration shown inFIGS. 1A and 1B, angle α (alpha) is greater than 60 degrees, such thateach of the arcuate members, taken separately, subtends at least 60degrees around central longitudinal axis 64.

For some applications, stent-graft 20 is self-expanding, in which casethe radially-expanded state is a relaxed state of the stent-graft. Forthese applications, lateral tube 50 is typically self-protruding frommain tube 40. As used in the present application, including in theclaims, a “central longitudinal axis” of an elongate structure is theset of all centroids of transverse cross-sectional sections of thestructure along the structure. Thus the cross-sectional sections arelocally perpendicular to the central longitudinal axis, which runs alongthe structure. (If the structure is circular in cross-section, thecentroids correspond with the centers of the circular cross-sectionalsections.)

Typically, structural strut members 30 comprise a metal, such as aflexible metal, an elastic metal, stainless steel, or a superelasticalloy (such as Nitinol). Graft member 32 comprises one or morebiologically-compatible substantially blood-impervious flexible sheets34, and is attached (such as by stitching) to at least a portion ofstructural strut members 30, on either side of the surfaces defined bythe support element, so as to define lumens 42 and 62. The flexiblesheets may comprise, for example, a polymeric material (e.g., apolyester, or polytetrafluoroethylene), a textile material (e.g.,polyethylene terephthalate (PET), or expanded polytetrafluoroethylene(ePTFE)), natural tissue (e.g., saphenous vein or collagen), or acombination thereof.

Typically, arcuate members 70 are disposed with 3 mm of a distal end ofstructural strut members 30 that define lateral tube 50, whenstent-graft 20 is in the radially-expanded state. For example, arcuatemembers 70 may be disposed at the distal end of structural strut members30 that define lateral tube 50, when stent-graft 20 is in theradially-expanded state, such as shown in FIG. 1A. Typically, arcuatemembers 70 are disposed with 3 mm of a distal end of a portion of graftmember 32 that defines lateral tube 50, when stent-graft 20 is in theradially-expanded state. For example, arcuate members 70 may be disposedat the distal end of the portion of graft member 32 that defines lateraltube 50, when stent-graft 20 is in the radially-expanded state, such asshown in FIG. 1A.

FIG. 1B shows stent-graft 20 when main tube 40 is in a radially-expandedstate thereof and lateral tube 50 is in a compressed delivery statethereof. For sonic applications, such as shown in FIG. 1B, when maintube 40 is in a radially-expanded state thereof and lateral tube 50 isin a compressed delivery state thereof, arcuate members 70 define aportion of a generally tubular outer surface of main tube 40.

Typically, arcuate members 70 are arranged so as to provide respectivecircumferential gaps 80 between circumferentially-adjacent ones ofarcuate members 70, when stent-graft 20 is in the radially-expandedstate. For example, in the configuration shown in FIG. 1A, arcuatemembers 70 are arranged so as to provide exactly two circumferentialgaps 80. For some applications, arcuate members 70 collectively subtendno more than 350 degrees around central longitudinal axis 64, such as nomore than 340 degrees, when stent-graft 20 is in the radially-expandedstate. For example, as shown in FIG. 1A, in the configuration shown inFIGS. 1A and 1B, structural strut members 30 that define lateral tube 50are shaped so as to define exactly two non-contiguous arcuate members70, each of which subtends an angle α (alpha) around centrallongitudinal axis 64, such that they collectively subtend an angle equalto 2α (twice alpha), which is no more than 350 degrees. For someapplications, each of the circumferential gaps measures at least 10degrees, such as at least 20 degrees, when stent-graft 20 is in theradially-expanded state.

For some applications, such as shown in FIG. 1A (and in FIGS. 2A, 3A,4A, and 5A-B, described hereinbelow), arcuate members 70 are disposed ata same axial position along lateral tube 50, when stent-graft 20 is inthe radially-expanded state. For some of these applications, such asshown in FIG. 1A, respective areas 82 of lateral tube 50, which (a)circumferentially correspond with the gaps and (b) extend from the axialposition of arcuate members 70 along at least 50%, such as at least 60%,e.g., 100% (as shown in FIG. 1A), of a distance D between the axialposition of arcuate members 70 and junction 60, are free from structuralstrut members 30, when stent-graft 20 is in the radially-expanded.state.

For some applications, one or more of structural strut members 30 (theseone or more structural strut members are labeled 86 in the figures)surround proximal end 54 of lateral tube 50 at junction 60. For someapplications, one or more of structural strut members 30 (these one ormore structural strut members are labeled 86 in the figures) surroundproximal end 54, such as completely (i.e., around 360 degrees) surroundproximal end 54, when stent-graft 20 is in the radially-expanded state.

For some applications, structural strut members 30 that define lateraltube 50 are shaped so as to define respective linking members 84 forarcuate members 70. Linking members 84 link arcuate members 70 tojunction 60, such as with the one or more structural strut members 86that surround proximal end 54, for applications in which thesesurrounding strut members are provided. (It is to be understood that notall of structural strut members 30 that define lateral tube 50necessarily are shaped so as to define linking members 84; typically,only a portion of structural strut members 30 that define lateral tube50 are shaped so as to define linking members 84.) For someapplications, linking members 84 form respective angles β (beta) withthe respective arcuate members 70, which angles have an average of 30 to90 degrees, such as 85 to 90 degrees, e.g., 90 degrees, when stent-graft20 is in the radially-expanded state. For some applications, an averagelength of linking members 84 equals at least 80% of a length of lateraltube 50.

For some applications, such as shown in FIG. 1A (and in FIGS. 2A-B, 3A,4A, and 5A-B, described hereinbelow), when stent-graft 20 is in theradially-expanded state, lateral tube 50 is free from structural strutmembers 30, except for arcuate members 70 and linking members 84, in anarea that (a) extends entirely around central longitudinal axis 64 and(b) extends from distal end 52 of lateral tube 50 along at least 50% ofa distance between distal end 52 of lateral tube 50 and junction 60. Forsome of these applications, such as also shown in FIG. 1A (and in FIGS.2A-B, 3A, 4A, and 5A-B, described hereinbelow), when stent-graft 20 isin the radially-expanded state, lateral tube 50 is free from structuralstrut members 30, except for arcuate members 70, linking members 84. andany of structural strut members 30 that surround proximal end 54 oflateral tube 50 at junction 60.

For some applications, structural strut members 30 that define main tube40 are arranged as a plurality of circumferential stent springs 88, eachof which is shaped so as to define a plurality of stent cells 90. (It isto be understood that not all of structural strut members 30 that definemain tube 40 necessarily are shaped so as to define stent springs 88;for some applications, only a portion of structural strut members 30that define main tube 40 are shaped so as to define stent springs 88.)Typically, axially-adjacent ones of the stent springs are not in contactwith one another, when stent-graft 20 is in the radially-expanded state.For some applications, stent cells 90 are diamond-shaped, whenstent-graft 20 is in the radially-expanded state. For some applications,the diamond-shaped stent cells 90 have respective, different dimensions,when stent-graft 20 is in the radially-expanded state.

Typically, one of stent cells 90 of one of stent springs 88 is definedby the one or more of structural strut members 30 that completelysurround proximal end 54 of lateral tube 50 at junction 60, whenstent-graft 20 is in the radially-expanded state.

For some applications, a ratio of (a) an average circumference of maintube 40 and (b) an average circumference of lateral tube 50 is between1:1 and 5:1, when stent-graft 20 is in the radially-expanded state. Forsome applications, a length of lateral tube 50 is between 10% and 30% ofan average circumference of lateral tube 50, when stent-graft 20 is inthe radially-expanded state. For some applications, a circumference oflateral tube 50 at proximal end 54 of lateral tube 50 is between 5% and30% greater than a circumference of lateral tube 50 at distal end 52 oflateral tube 50, when stent-graft 20 is in the radially-expanded state.For sonic applications, a length of main tube 40 is 4 to 15 cm.

For some applications, an angle between central longitudinal axis 64 oflateral tube 50 and a central longitudinal axis of main tube 40 isgreater than 80 degrees, when stent-graft 20 is in the radially-expandedstate. For some applications, an angle between central longitudinal axis64 of lateral tube 50 and a longitudinal axis of main tube 40 is between60 and 80 degrees, when stent-graft 20 is in the radially-expandedstate. For some applications, an angle between central longitudinal axis64 of lateral tube 50 and a longitudinal axis of main tube 40 is between30 and 60 degrees, when stent-graft 20 is in the radially-expandedstate.

For some applications, stent-graft 20 comprises two or more (e.g.,exactly two or exactly three) lateral tubes 50, such as describedhereinbelow with reference to FIGS. 3A-B. mutatis mutandis.

Reference is now made to FIG. 2A, which is a schematic illustration ofanother configuration of stent-graft 20, in accordance with anapplication of the present invention. In this configuration, structuralstrut members 30 that define lateral tube 50 are shaped so as to defineexactly four non-contiguous arcuate members 70, each of which subtendsan angle α (alpha) around central longitudinal axis 64, such that theycollectively subtend an angle equal to 4α (four times alpha). Arcuatemembers 70 are arranged so as to provide exactly four circumferentialgaps 80.

Reference is now made to FIG. 2B, which is a schematic illustration ofyet another configuration of stent-graft 20, in accordance with anapplication of the present invention. In this configuration, at leasttwo of arcuate members 70 are disposed at respective different axialpositions along lateral tube 50, when stent-graft 20 is in theradially-expanded state.

Reference is now made to FIGS. 3A and 3B, which are schematicillustrations of a portion of an endovascular stent-graft 120, inaccordance with an application of the present invention. Other than asdescribed below, stent-graft 120 is identical to stent-graft 20,described hereinabove with reference to FIGS. 1A-B and 2A-B, and mayimplement any of the features of stent-graft 20.

As mentioned above with reference to FIGS. 1A-B, for some applications,structural strut members 30 that define main tube 40 are arranged as aplurality of circumferential stent springs 88, each of which is shapedso as to define a plurality of stent cells 90. Typically,axially-adjacent ones of the stent springs are not in contact with oneanother, when stent-graft 20 is in the radially-expanded state.Typically, one of stent cells 90 of one of stent springs 88 is definedby the one or more of structural strut members 30 that completelysurround proximal end 54 of lateral tube 50 at junction 60, whenstent-graft 20 is in the radially-expanded state. For some applications,stent cells 90 are diamond-shaped, when stent-graft 20 is in theradially-expanded state. For some applications, the diamond-shaped stentcells 90 have respective, different dimensions, when stent-graft 20 isin the radially-expanded state.

In the configuration shown in FIGS. 3A-B, a largest one of stent cells90 (labeled 90A) (e.g., the diamond-shaped stent cells) is at least 100%greater in surface area than a smallest one of stent cells 90 (labeled90B) (e.g., the diamond-shaped stent cells), which largest one of stentcells 90A is the one of the stent cells 90 that is defined by the one ormore of structural strut members 30 that completely surround proximalend 54 of lateral tube 50 at junction 60, when stent-graft 20 is in theradially-expanded state.

As mentioned above regarding stent-graft 20, for some applications,stent-grail 120 comprises two or more (e.g., exactly two or exactlythree) lateral tubes 50. For these applications, lateral tube 50 is afirst lateral tube 50, distal and proximal ends 52 and 54 are firstdistal and proximal ends 54 and 54, junction 60 is a first junction 60,lateral lumen 62 is a first lateral lumen 62, central longitudinal axis64 is a first central longitudinal axis 64, and arcuate members 70 arefirst arcuate members 70. Structural strut members 30 and graft member32 are arranged so as to define, when stent-graft 20 is in theradially-expanded state, a second lateral tube 150, which (a) has (i) asecond distal end 152 and (ii) a second proximal end 154 that is joinedto lateral wall 56 of main tube 40 at a second junction 160, (b) isshaped so as to define a second lateral lumen 162 that is in fluidcommunication with main lumen 42, and (c) defines a second centrallongitudinal axis 164. When stent-graft 20 is in the radially-expandedstate, structural strut members 30 that define second lateral tube 150are shaped so as to define two to four non-contiguous second arcuatemembers 170, which (a) are centered around second central longitudinalaxis 164, and (c) collectively subtend at least 150 degrees aroundsecond central longitudinal axis 164.

For some applications, the smallest one of stent cells 90B (e.g., thediamond-shaped stent cells) completely surrounds second proximal end 154of second lateral tube 150 at second junction 160, when stent-graft 20is in the radially-expanded state. For some applications, an averagecircumference of second lateral tube 150 is less than an averagecircumference of first lateral tube 50.

For other applications, such as shown in FIGS. 6A-B, structural strutmembers 30 and graft member 32 are arranged so as to define, whenstent-graft 20 is in the radially-expanded state, second lateral tube150, and the smallest one of stent cells 90B (e.g., the diamond-shapedstent cells) does not surround second proximal end 154 of second lateraltube 150 at second junction 160, when stent-graft 20 is in theradially-expanded state. For these applications, an averagecircumference of second lateral tube 150 may be equal to an averagecircumference of first lateral tube 50.

Reference is now made to FIGS. 4A and 4B, which are schematicillustrations of a portion of an endovascular stent-graft 220, inaccordance with an application of the present invention. Stent-graft 220may implement any of the features of stent-graft 20, describedhereinabove with reference to FIGS. 1A-B and 2A-B, and/or stent-graft120, described hereinabove with reference to FIGS. 3A-B.

As mentioned above, for some applications, structural strut members 30that define lateral tube 50 are shaped so as to define respectivelinking members 84 for arcuate members 70, which linking members 84 linkarcuate members 70 to junction 60, such as with the one or morestructural strut members 86 that surround proximal end 54, forapplications in Which these surrounding strut members are provided. Forsome applications, such as shown in FIG. 4A, linking members 84 formrespective angles γ (gamma) with the respective arcuate members 70,which angles have an average of 30 to 60 degrees (e.g., about 45degrees), when stent-graft 20 is in the radially-expanded state. Forsome applications, proximal portions of linking members 84 are generallyasymptotic with junction 60, and with the one or more structural strutmembers 86 that surround proximal end 54, for applications in whichthese surrounding strut members are provided.

In this configuration, distal end 52 of lateral tube 50 rotates duringthe transition from the compressed delivery state to theradially-expanded state. As a result, in the crimped configuration shownin FIG. 4B (in which lateral tube is in the radially-compressed statethereof), linking members 84 do not overlap one another, which mightcause an increased crossing profile of stent-graft 220.

For some applications, one or more (e.g., all) of arcuate members 70 areshaped so as to define respective jointed locations 292, which areconfigured such that the arcuate members fold at the jointed locations292 when main tube 40 is radially compressed. Without such foldingprotrusions, the arcuate members might plastically deform at arbitrarylocations therealong when the main tube is radially compressed. Forsonic applications, each of the jointed locations 292 is at a locationalong its respective arcuate member 70 that is within a number ofdegrees of a circumferential center 294 of the arcuate member aroundcentral longitudinal axis 64, which number of degrees is equal to 40% ofa total number of degrees of the arcuate member, such as at thecircumferential center of the arcuate member. For some applications,arcuate members 70 of stent-graft 20 or 120, described hereinabove withreference to FIGS. 1A-3B, are shaped so as to define respective jointedlocations 292.

For some applications, stent-graft 220 comprises two or more (e.g.,exactly two or exactly three) lateral tubes 50, such as describedhereinbelow with reference to FIGS. 3A-B, mutatis mutandis.

Reference is now made to FIGS. 5A and 5B, which are schematicillustrations of portions of stent-grafts 20 and 220, respectively, inaccordance with respective applications of the present invention. Asmentioned above, for some applications, structural strut members 30 thatdefine lateral tube 50 are shaped so as to define respective linkingmembers 84 for arcuate members 70, which linking members 84 link arcuatemembers 70 to junction 60.

For some applications, as shown in FIGS. 5A and 5B, when stent-graft 20is in the radially-expanded state, respective points 300 on linkingmembers 84 and respective juncture points 302 between linking members 84and arcuate members 70 define respective lines 304 (it is to beunderstood that points 300 and 302 and lines 304 are not actualstructural features of the stent-grafts, but are instead abstractgeometric elements used to describe the physical properties of thedevice). Lines 304 form respective angles δ (delta) with the respectivearcuate members 70. The angles δ (delta) have an average of 30 to 90degrees. Points 300 on linking members 84 are at 30% of a distance D2between the axial position of arcuate members 70 and junction 60. Forsome applications, such as shown in FIG. 5A, the average is 85 to 90degrees, e.g., 90 degrees, while for other applications, such as shownin FIG. 5B, the average is 30 to 60 degrees, e.g., about 45 degrees.

For some applications, such as labeled in FIG. 5A and also shown inFIGS. 1A, 2A, and 3A, juncture point 302 between each of the linkingmembers 84 and its respective arcuate member is at a location along thearcuate member that is within a number of degrees of circumferentialcenter 294 of the arcuate member around central longitudinal axis 64,which number of degrees is equal to 40% of a total number of degrees ofthe arcuate member, such as at the circumferential center of the arcuatemember. For other applications, such as labeled in FIG. 5B and alsoshown in FIG. 4A,

Reference is now made to FIGS. 6A-B, which are schematic illustrationsof exemplary deployments of stent-graft 120, in accordance withrespective applications of the present invention. Stent-graft 120, andthe other stent-grafts described herein, may also be used to treat ablood vessel suffering from a dissection, or, more generally, apathologically dilated aorta. The techniques described with reference toFIGS. 6A-B may also be used to deploy stent-grafts 20 and 220.

In the configuration shown in FIG. 6A, stent-graft 120 is shown deployedin the vicinity of a sub-renal (e.g., juxtarenal) abdominal aorticaneurysm 400 of an abdominal aorta. In this deployment, an averagecircumference of second lateral tube 150 is equal to an averagecircumference of first lateral tube 50.

In the configuration shown in FIG. 6B, stent-graft 120 is shown deployedin an aortic arch 500 and a brachiocephalic artery 503. Moreparticularly, main tube 40 is shown deployed mostly in aortic arch 500,with a narrower proximal end 510 of the main tube deployed inbrachiocephalic artery 503. For some applications, a circumference ofproximal end 510 of main tube 40 is 3 to 10 cm, when stent-graft 120 isin the radially-expanded state. Alternatively or additionally, for someapplications, a circumference of a distal end of main tube 40 is 6 to 12cm, when stent-graft 120 is in the radially-expanded state.Alternatively, narrower proximal end 510 of main tube 40 may beconfigured to be disposed in another branch of aortic arch 500, such asa left common carotid artery 512 or a left subclavian artery 514.Optionally, the techniques described herein are used in combination withthe techniques described in US Patent Application Publication2013/0013050, which is incorporated herein by reference. (It is notedthat in the deployment shown in FIG. 6B, blood flow to left subclavianartery 514 is blocked by stent-graft 120. The left subclavian artery iseither “sacrificed” (i.e. via occlusion), or surgically anastomosed toleft common carotid artery 512, or possibly to another source artery,such as the right common carotid artery. Alternatively, stent-graft 120may he shaped so as to define an additional lateral tube 50, and anadditional branching stent-graft may be deployed into left subclavianartery 514.)

The deployment is typically performed in a transvascular (typicallypercutaneous) procedure using one or more guidewires and an elongatedelivery tube that is sized to hold stent-graft 120 in theradially-compressed delivery state. For some applications, a ratio of(a) an average circumference of main tube 40 when in theradially-expanded state thereof to (b) an inner circumference of thedelivery tube is at least 5. Typically, after stent-graft 120 ispositioned at the desired anatomical site, the sheath is withdrawnproximally, exposing stent-graft 120 and allowing the stent-graft toself-expand, or be expanded by plastic deformation using a balloon, intothe radially-expanded state. The deployment may be performed usingdeployment techniques known in the art and/or described in any of thepatent applications publications and patents incorporated hereinbelow byreference.

For some applications, such as shown in FIG. 6A, first and secondlateral tubes 50 and 150 are positioned in respective branching bloodvessels, such as branching visceral arteries, e.g., renal arteries 402Aand 4029. For other applications, such as shown in FIG. 6B, one of firstand second lateral tubes 50 and 150 is positioned in the main bloodvessel and the other in a branching blood vessel, e.g., first lateraltube 50 is positioned in aortic arch 500, facing upstream, and secondlateral tube 150 is positioned in brachiocephalic artery 503.

For some applications, two or more branching stent-grafts, such as twobranching stent-grafts 410A and 410B, are deployed through a portionmain lumen 42 of main tube 40 and through first and second laterallumens 62 and 162 of first and second lateral tubes 50 and 150,respectively, and into their respective arteries, so as to formrespective blood-tight seals with first and second lateral tubes 50 and150. For example, as shown in FIG. 6A, branching stent-grafts 410A and410B are positioned in renal arteries 402A and 402B, respectively, or,as shown in FIG. 69, branching stent-grafts 410A and 410B are positionedin an ascending aorta 516 and left common carotid artery 512,respectively.

For example, the branching stent-grafts may be deployed using respectiveguidewires and cannulae, such as described in PCT/IL2014/050973, filedNov. 6, 2014, which published as WO 2015/075708, and which isincorporated herein by reference, with respect to FIGS. 13E-J thereof.As a result, in the deployment shown in FIG. 6A, stent-graft 120 andbranching stent-grafts 410A and 410B together define a fluid flow paththrough the aorta and the renal arteries, and in the deployment shown inFIG. 6B, stent-graft 120 and branching stent-grafts 410A and 410Btogether define a fluid flow path through aortic arch 500 andbrachiocephalic artery 503 and left common carotid artery 512.Typically, the branching stent-grafts are transvascularly introducedwhen in respective radially-compressed delivery states, and aretransitioned to respective radially-expanded states.

As mentioned above, for some applications the stent-graft is shaped soas to define one or more additional lateral tubes 50. For theseapplications, one or more additional branching stent-grafts may bedeployed into additional branching visceral arteries, such as, for thedeployment shown in FIG. 6A, the superior mesenteric artery (SMA) and/orthe celiac artery, or, for the deployment shown in FIG. 68, leftsubclavian artery 514, and sealingly coupled to the additional lateraltube(s). Typically, a main stent-graft is deployed and blood-tightlysealingly coupled to a proximal end of stent-graft 120 to extend thefluid flow path past the aneurysm, such as shown in FIG. 13J of theabove-mentioned PCT Application PCT/IL2014/050973, mutatis mutandis.Alternatively, stent-graft 120 may be shaped so as to define afenestration to allow blood flow to the SMA.

The scope of the present invention includes embodiments described in thefollowing patents and patent applications, which are assigned to theassignee of the present application and are incorporated herein byreference. In an embodiment, techniques and apparatus described in oneor more of the following patent applications are combined withtechniques and apparatus described herein. In particular, thestent-grafts described herein may be used as components of thestent-graft systems described in the following patent and patentapplications, and deployed as described as described in the followingpatent and patent applications, mutatis mutandis.

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It will be appreciated by persons skilled in the art that the presentinvention is not limited to what has been particularly shown anddescribed hereinabove. Rather, the scope of the present inventionincludes both combinations and subcombinations of the various featuresdescribed hereinabove, as well as variations and modifications thereofthat are not in the prior art, which would occur to persons skilled inthe art upon reading the foregoing description.

1. Apparatus comprising an endovascular stent-graft, which is configuredto transition from a radially-compressed delivery state to aradially-expanded state, and which comprises: a plurality of structuralstrut members; and a graft member, which comprises one or moresubstantially blood-impervious flexible sheets, and which is fixed tothe structural strut members, wherein the structural strut members andthe graft member are arranged so as to define, when the stent-graft isin the radially-expanded state: a main tube, which is shaped so as todefine a main lumen, and a lateral tube, which (a) has (i) a distal endand (ii) a proximal end that is joined to a lateral wall of the maintube at a junction, (b) is shaped so as to define a lateral lumen thatis in fluid communication with the main lumen, and (c) defines a centrallongitudinal axis, and wherein, when the stent-graft is in theradially-expanded state, the structural strut members that define thelateral tube are shaped so as to define two to four non-contiguousarcuate members, which (a) are centered around the central longitudinalaxis, and (b) collectively subtend at least 150 degrees around thecentral longitudinal axis.
 2. The apparatus according to claim 1,wherein the arcuate members collectively subtend at least 180 degreesaround the central longitudinal axis, when the stent-graft is in theradially-expanded state.
 3. The apparatus according to claim 2, whereinthe arcuate members collectively subtend at least 210 degrees around thecentral longitudinal axis, when the stent-graft is in theradially-expanded state.
 4. The apparatus according to claim 1, whereinat least one of the arcuate members alone subtends at least 60 degreesaround the central longitudinal axis, when the stent-graft is in theradially-expanded state.
 5. The apparatus according to claim 1, whereinthe arcuate members are disposed at a same axial position along thelateral tube, when the stent-graft is in the radially-expanded state. 6.The apparatus according to claim 1, wherein at least two of the arcuatemembers are disposed at respective different axial positions along thelateral tube, when the stent-graft is in the radially-expanded state. 7.The apparatus according to claim 1, wherein the arcuate members aredisposed with 3 mm of a distal end of the structural strut members thatdefine the lateral tube, when the stent-graft is in theradially-expanded state.
 8. The apparatus according to claim 7, whereinthe arcuate members are disposed at the distal end of the structuralstrut members that define the lateral tube, when the stent-graft is inthe radially-expanded state.
 9. The apparatus according to claim 1,wherein the arcuate members are disposed with 3 mm of a distal end of aportion of the graft member that defines the lateral tube, when thestent-graft is in the radially-expanded state.
 10. The apparatusaccording to claim 9, wherein the arcuate members are disposed at thedistal end of the portion of the graft member that defines the lateraltube, when the stent-graft is in the radially-expanded state.
 11. Theapparatus according to claim 1, wherein when the main tube is in aradially-expanded state thereof and the lateral tube is in a compresseddelivery state thereof, the arcuate members define a portion of agenerally tubular outer surface of the main tube.
 12. The apparatusaccording to claim 1, wherein the apparatus further comprises abranching stent-graft, which is configured to form a blood-tight sealwith the lateral tube, when the stent-graft is in the radially-expandedstate and the branching stent-graft is in a radially-expanded state. 13.The apparatus according to claim 1, wherein a ratio of (a) an averagecircumference of the main tube and (b) an average circumference of thelateral tube is between 1:1 and 5:1, when the stent-graft is in theradially-expanded state.
 14. The apparatus according to claim 1, whereina length of the lateral tube is between 10% and 30% of an averagecircumference of the lateral tube, when the stent-graft is in theradially-expanded state.
 15. The apparatus according to claim 1, whereina circumference of the lateral tube at the proximal end of the lateraltube is between 5% and 30% greater than a circumference of the lateraltube at the distal end of the lateral tube. when the stent-graft is inthe radially-expanded state.
 16. The apparatus according to claim 1,wherein an angle between the central longitudinal axis of the lateraltube and a central longitudinal axis of the main tube is greater than 80degrees, when the stent-graft is in the radially-expanded state.
 17. Theapparatus according to claim 1, wherein an angle between the centrallongitudinal axis of the lateral tube and a central longitudinal axis ofthe main tube is between 60 and 80 degrees, when the stent-graft is inthe radially-expanded state.
 18. The apparatus according to claim 1,wherein an angle between the central longitudinal axis of the lateraltube and a central longitudinal axis of the main tube is between 30 and60 degrees, when the stent-graft is in the radially-expanded state. 19.The apparatus according to claim 1, wherein the main tube has proximaland distal ends, and wherein a circumference of the proximal end of themain tube is 3 to 10 cm, when the stent-graft is in theradially-expanded state.
 20. The apparatus according to claim 19,wherein a circumference of the distal end of the main tube is 6 to 12cm, when the stent-graft is in the radially-expanded state.
 21. Theapparatus according to claim 1, wherein a length of the main tube is 4to 15 cm.
 22. The apparatus according to claim 1, wherein the one ormore of the structural strut members comprise a flexible metal.
 23. Theapparatus according to claim 22, wherein the metal comprises asuperelastic alloy.
 24. The apparatus according to claim 23, wherein thealloy comprises Nitinol.
 25. The apparatus according to claim 1, whereinthe one or more flexible sheets comprise polyethylene terephthalate. 26.The apparatus according to claim 1, wherein the one or more flexiblesheets comprise expanded polytetratluoroethylene (PTFE).
 27. Theapparatus according to any one of claims 1-26, wherein the arcuatemembers are arranged so as to provide respective circumferential gapsbetween circumferentially-adjacent ones of the arcuate members, when thestent-graft is in the radially-expanded. state.
 28. The apparatusaccording to claim 27, wherein the arcuate members collectively subtendno more than 350 degrees around the central longitudinal axis, when thestent-graft is in the radially-expanded state.
 29. The apparatusaccording to claim 28, wherein the arcuate members collectively subtendno more than 340 degrees around the central longitudinal axis, when thestent-graft is in the radially-expanded state.
 30. The apparatusaccording to claim 27, wherein each of the circumferential gaps measuresat least 10 degrees, when the stent-graft is in the radially-expandedstate.
 31. The apparatus according to claim 30, wherein each of thecircumferential gaps measures at least 20 degrees, when the stent-graftis in the radially-expanded state.
 32. The apparatus according to claim27, wherein the arcuate members are disposed at a same axial positionalong the lateral tube, when the stent-graft is in the radially-expandedstate.
 33. The apparatus according to claim 32, wherein respective areasof the lateral tube, which (a) circumferentially correspond with thegaps and (b) extend from the axial position of the arcuate members alongat least 50% of a distance between the axial position of the arcuatemembers and the junction, are free from the structural strut members,when the stent-graft is in the radially-expanded state.
 34. Theapparatus according to claim 33, wherein the respective areas extendfrom the arcuate members along 60% of the distance.
 35. The apparatusaccording to claim 34, wherein the respective areas extend from thearcuate members along 100% of the distance.
 36. The apparatus accordingto any one of claims 1-26, wherein the structural strut members thatdefine the lateral tube are shaped so as to define respective linkingmembers for the arcuate members, which linking members link the arcuatemembers to the junction.
 37. The apparatus according to claim 36,wherein, when the stem-graft is in the radially-expanded state, thelateral tube is free from the structural strut members, except for thearcuate members and the linking members, in an area that (a) extendsentirely around the central longitudinal axis and (b) extends from thedistal end of the lateral tube along at least 50% of a distance betweenthe distal end of the lateral tube and the junction.
 38. The apparatusaccording to claim 37, wherein, when the gent-graft is in theradially-expanded state, the lateral tube is free from the structuralstrut members, except for the arcuate members, the linking members, andany of the structural strut members that surround the proximal end ofthe lateral tube at the junction.
 39. The apparatus according to claim36, wherein an average length of the linking members equals at least 80%of a length of the lateral tube, when the stent-graft is in theradially-expanded state.
 40. The apparatus according to claim 36,wherein, when the stent-graft is in the radially-expanded state,respective points on the linking members and respective juncture pointsbetween the link members and the arcuate members define respectivelines, which lines form respective angles with the respective arcuatemembers, which angles have an average of 30 to 90 degrees, and whichpoints on the linking members are at 30% of a distance between the axialposition of the arcuate members and the junction.
 41. The apparatusaccording to claim 40, wherein an average length of the linking membersequals at least 80% of a length of the lateral tube, when thestent-graft is in the radially-expanded state.
 42. The apparatusaccording to claim 40, wherein the average is 85 to 90 degrees.
 43. Theapparatus according to claim 42, wherein the average is 90 degrees. 44.The apparatus according to claim 40, wherein the average is 30 to 60degrees.
 45. The apparatus according to claim 40, wherein the linkingmembers form respective angles with the respective arcuate members,which angles have an average of 30 to 90 degrees, when the stent-graftis in the radially-expanded state.
 46. The apparatus according to claim45, wherein the average is 85 to 90 degrees.
 47. The apparatus accordingto claim 46, wherein the average is 90 degrees.
 48. The apparatusaccording to claim 45, wherein the average is 30 to 60 degrees.
 49. Theapparatus according to claim 36, wherein each of the linking members isconnected to its respective arcuate member at a juncture point at alocation along the arcuate member that is within a number of degrees ofa circumferential center of the arcuate member around the centralcircumferential axis, which number of degrees is equal to 40% of a totalnumber of degrees of the arcuate member.
 50. The apparatus according toclaim 49, wherein the location along the arcuate member is at thecircumferential center of the arcuate member.
 51. The apparatusaccording to claim 36, wherein, when the stent-graft is in theradially-expanded state, one or more of the structural strut members (a)completely, surround the proximal end of the lateral tube at thejunction and (b) are connected to the linking members.
 52. The apparatusaccording to any one of claims 1-26, wherein one or more of thestructural strut members completely surround the proximal end of thelateral tube at the junction, when the stent-graft is in theradially-expanded state.
 53. The apparatus according to claim 52,wherein the structural strut members that define the main tube areshaped so as a plurality of circumferential stent springs, each of whichis shaped so as to define a plurality of stent cells, and wherein one ofthe stent cells of one of the circumferential stent springs is definedby the one or more of the structural strut members that completelysurround the proximal end of the lateral tube at the junction, when thestent-graft is in the radially-expanded state.
 54. The apparatusaccording to claim 53, wherein the stent cells of the one of thecircumferential stent springs are diamond-shaped, when the stent-graftis in the radially-expanded state.
 55. The apparatus according to claim54, wherein the diamond-shaped stent cells have respective, differentdimensions, when the stent-graft is in the radially-expanded state. 56.The apparatus according to claim 55, wherein a largest one of thediamond-shaped stent cells is at least 100% greater in surface area thana smallest one of the diamond-shaped stent cells, which largest one ofthe diamond-shaped stent cells is the one of the stent cells that isdefined by the one or more of the structural strut members thatcompletely surround the proximal end of the lateral tube at thejunction, when the stent-graft is in the radially-expanded state. 57.The apparatus according to claim 56, wherein the lateral tube is a firstlateral tube, the distal and proximal ends are first distal and proximalends, the junction is a first junction, the lateral lumen is a firstlateral lumen, the central longitudinal axis is a first centrallongitudinal axis, and the arcuate members are first arcuate members,wherein the structural strut members and the graft member are arrangedso as to define, when the stent-graft is in the radially-expanded state,a second lateral tube, which (a) has (i) a second distal end and (ii) asecond proximal end that is joined to the lateral wall of the main tubeat a second junction, (b) is shaped so as to define a second laterallumen that is in fluid communication with the main lumen, and (c)defines a second central longitudinal axis, wherein, when thestent-graft is in the radially-expanded state, the structural strutmembers that define the second lateral tube are shaped so as to definetwo to four non-contiguous second arcuate members, which (a) arecentered around the second central longitudinal axis, and (b)collectively subtend at least 150 degrees around the second centrallongitudinal axis, and wherein the smallest one of the diamond-shapedstent cells completely surrounds the second proximal end of the secondlateral tube at the second junction, when the stent-graft is in theradially-expanded state.
 58. A method for treating a subject,comprising: transvascularly introducing an endovascular stent-graft intoa blood vessel of the subject while the stent-graft is in aradially-compressed delivery state, which stent-graft comprises (a) aplurality of structural strut members, and (b) a graft member, whichcomprises one or more substantially blood-impervious flexible sheets,and which is fixed to the structural strut members; and transitioningthe stent-graft to a radially-expanded state, in which: the structuralstrut members and the graft member are arranged so as to define (x) amain tube, which is shaped so as to define a main lumen, and (y) alateral tube, which (a) has (i) a distal end and (ii) a proximal endthat is joined to a lateral wall of the main tube at a junction, (b) isshaped so as to define a lateral lumen that is in fluid communicationwith the main lumen, and (c) defines a central longitudinal axis, andthe structural strut members that define the lateral tube are shaped soas to define two to four non-contiguous arcuate members, which (a) arecentered around the central longitudinal axis, and (b) collectivelysubtend at least 150 degrees around the central longitudinal axis.